Current teacher here. You cannot place a finger on a student. In a case like this you would have to call admin for them to send someone who has been trained in "physical intervention". About 10 years ago the district was sued because a teacher tried to stop a fight by pulling another student off of another. When doing this, the student who was previously on the bottom got up and sucker punched the student being held by the teacher. The parent of the student who got sucker punched sued the district and won. Today kids can leave class, smoke in the bathrooms, bring a knife to school, and all a teacher can do is call someone. If a student is yelling in class, throwing things, standing on desks, reading a porn magazine, all a teacher can do is call someone. A teacher can't even take things out of student hands, can't stop them from running down the halls, can't pick things up off the ground a student has dropped... nothing. All we can do is ask them to stop, or call the office.